The Composite, Aug. 29 -- The number on the tape said the Nasdaq Composite was having a bad Friday. The number the week before told a different story.

the broadest measure of the Nasdaq-listed universe, encompassing more than 3,000 companies across technology, biotechnology, consumer discretionary, and other sectors - closed Friday down 0.52% at 26,402.42. The session's decline came after Federal Reserve Chair Kevin Warsh delivered remarks at the Jackson Hole symposium in Wyoming that were more cautious on inflation than traders had positioned for. For the week, the Composite still posted a 0.9% gain, a result that would not exist without NVIDIA Corporation's extraordinary Thursday surge.

The Nasdaq Composite is a different instrument f...